Slow cooker in the prior art is generally of simple design, and typically includes an inner pot and a lid thereon. Further, a fastening clip can be provided and hinged on a handle, such that the lid can be compressed tightly by clipping of the fastening clip. However, it is inconvenient to engage or release the fastening device. Besides, the sealing is not so perfect since the lid is compressed at one point only, which effects the quality of food cooked. On the other hand, a larger gap typically exists between the inner pot and the side wall, so that the inner pot cannot be placed steadily and protected well, and therefore it is not so safe when carrying the cooker. It is obviously significant to make further improvements to the design of the slow cooker for convenience and better cooking.